This invention relates to the field of devices for handling crucibles and more particularly to the field of devices that handles crucibles while they are being lifted in and out of the melting furnace.
Crucibles are expensive, they are made with very thin walls, and the walls become brittle after being in the furnace awhile. Thus, crucibles can be easily broken. In a foundry, one of the most dangerous times in dealing with crucibles is when the crucible is lifted out of the melting furnace. When the crucible is being lifted, it can be easily bumped into the melting furnace wall and break or crack or do damage to the furnace. Further, the heavy weight of the crucible makes it a safety hazard to the individuals lifting it. Thus, one of the objectives of this invention is to create a system that can lift a crucible from the melting furnace safely and without damage to the crucible or furnace. The device is also designed to place a new crucible back in the melting furnace without damaging the crucible and insuring a proper vertical placement.
In order for the lifter to ensure a safe handling of the crucible without damaging the crucible or allowing the crucible to strike against the furnace, the lifter must ensure a straight vertical lift of the crucible without having the crucible swing or make other potential damaging movements. The lifter must also be able to lift the crucible when there is a minimum clearance between the furnace walls and the crucible of two to three inches. These objectives must also be obtained with a device that is easy to use, inexpensive to build and maintain.
The features that allow the inventors lifter to achieve his objectives is that the lifter has a fabricated steel assembly that precisely positions, aligns, and engages and holds in place flexible rigging around the base of the crucible. Once this flexible rigging is aligned by the steel assembly, the crucible can be safely and securely lifted and manipulated.
The invention is a device that is used to securely hold a crucible for lifting by a lifting device. It has a circular frame with a top bracing leg that ensures straight vertical lifting and proper alignment of the rigging. The frame diameter is slightly larger than the crucible. Vertical pieces extend downward from the top of the frame. At the bottom end of each of these vertical pieces a hinged piece is attached. On the hinged pieces, a bottom rigging retainer is attached. The bottom rigging retainer allows the rigging to freely pass through it. The bottom rigging retainer with the hinged piece form a loop through which the rigging is thread. The rigging securely holds the bottom of the crucible. A lifting device is attached to the riggings to lift the crucible. The frame can be made adjustable to fit many sizes of crucibles.